1. Technical Field
This invention relates to a remote control lever module for sensing movement of a lever. More particularly, the invention relates to a remote control lever module for sensing the angular position of a pedal lever for an electronic vehicle control system. The lever module may be further adapted to include hysteresis to simulate the feel of a purely mechanical linkage (i.e., a pedal lever connected to a throttle valve via a cable), and to sense engagement of the pedal lever by the operator.
2. Background Art
Vehicle engine control systems are known having a sensor, such as a potentiometer, connected to an accelerator pedal for measuring the displacement of the accelerator pedal. A force sensor, such as a resistive strain gauge, is connected to the accelerator pedal which is able to sense whether a force is being applied to the pedal, such as by the operator stepping thereon. The electronic control module (ECM) is programmed to sense the signal produced by the force sensor and cause the engine to idle if there is no force sensed, even if the potentiometer indicates displacement of the pedal. This reduces the possibility of unintended movement of the vehicle by a reason other than the operator stepping on the accelerator pedal.
Such vehicle engine control systems can require considerable effort to package and install in a vehicle since they require multiple connections to the pedal and a portion of the vehicle which is stationary with respect to the vehicle, such as the bulkhead. Also, the potentiometer can vary in size as the pedal is displaced, and can be located apart from the force sensor further complicating packaging of the system.
An accelerator control apparatus is also known including a single shaft which rotates in proportion to the displacement of an accelerator pedal. The shaft is coupled to a position sensor which measures the rotation of the shaft. The shaft is also linked to a pedal sensor switch which is opened and closed by movement of the shaft corresponding to initial displacement of the undepressed pedal and return of the displaced pedal to the undisplaced position. A comparison of the signals from the position sensor and pedal sensor can indicate the integrity of the apparatus. The apparatus can also include a dual coiled return spring having coils of approximately the same size. The single shaft and limited number of return spring coils can limit the sensitivity of the apparatus to external forces applied to the pedal.
An accelerating pedal is also known including a single shaft which rotates in proportion to the displacement of the pedal. The shaft can be coupled to a position sensor which measures the rotation of the shaft. The shaft includes a disk which rotates therewith. The disk fits between pads which are fixed to a housing within which the shaft rotates When the shaft rotates, the pads exert a frictional force on the disk to create a desired hysteresis effect. The surface of the pads which engage the disk, as well as the surfaces of the disk which engage the pad, must be finished to produce the desired hysteresis effect yet enable the return spring to backwardly rotate the shaft when the operator ceases to depress the pedal. This can limit the permissible variations in surface finishes of the disk and pads.